Losses And Efficiency Of A Motor; Losses And Efficiency Of A Power Drive System; Losses And Efficiency Of A Power Drive System With Installed Filter - Danfoss VLT AHF 005 Design Manual

Basic Operating Principle o...
1.80
1.60
1.40
1.20
1.00
0.80
0.60
3 3
0.40
0.20
0.00
0 10
1 100% load
2 50% load
3 25% load
Illustration 3.11 Frequency converter power loss data.
CDM relative losses (P
(n) [% of nominal speed].
100.00
98.00
96.00
94.00
1
2
92.00
3
90.00
0
1 100% load
2 50% load
3 25% load
Illustration 3.12 Frequency converter efficiency data.
CDM efficiency (η
(n) [% of nominal speed].
Interpolation of power loss
Determine the power loss at an arbitrary operating point
using 2-dimensional interpolation.

3.2.4 Losses and Efficiency of a Motor

The efficiency of a motor running at 50–100% of the
nominal motor speed and at 75–100% of the nominal
torque is practically constant. This is valid both when the
frequency converter controls the motor, or when the motor
runs directly on mains.
The efficiency depends on the type of motor and the level
of magnetization.
For more information about motor types, refer to the
motor technology brochure at www.vlt-drives.danfoss.com.
18
VLT
20 30 40 50 60 70
n [%]
) [%] versus speed
L, CDM
20 40 60
n [%]
) [%] versus speed
CDM(freq, load)
Danfoss A/S © 10/2016 All rights reserved.
®
Advanced Harmonic Filter AHF 005/AHF 010
3.2.5 Losses and Efficiency of a Power Drive
System
1
To estimate the power losses at different operating points
2 for a power drive system, sum the power losses at the
operating point for each system component:
3
•
Frequency converter.
•
80 90 100
Motor.
•
Auxiliary equipment.
3.2.6 Losses and Efficiency of a Power Drive
System with Installed Filter
The power loss of the VLT
AHF005/AHF010 is specified in 5 different operating points
as 0–100% load. The current load and power loss are
specified in each operating point. See Table 9.2 for power
losses.
The power loss in the AHF depends on the operating point
and is a function of the input current in the AHF. The
identification point of operation of the AHF is based on
the input current to the frequency converter. The input
current of the frequency converter equals the input current
to the AHF.
I =I
In,AHF In,VLT
80 100
The output current of the frequency converter consists of
the torque-producing component and the motor magneti-
zation component. Different factors affect the relationship
between the input current and output current of a
frequency converter. For example, part load causes a
significant difference between the 2 currents.
≠I
I
In,VLT out,VLT
Calculate the input current of the frequency converter with
this formula:
I =I
In,VLT out,VLT
•
I
frequency converter. Find the data in the
frequency converter design guide or VLT
ecoSmart.
•
Cos (phi): Motor power factor. Find the data on
the motor nameplate. Alternatively, use a
reference value from EN 50598, see Table 3.2.
•
f
operating frequency in the motor in the range 0–
1.
•
load
producing component or torque-producing
current in the motor in the range 0–1. The value
is typically from the design of the application.
®
Advanced Harmonic Filter
x cos(phi) x f [%] x load
motor
: Nominal output current from the
out,VLT
[%]: Percentage value of the nominal
motor
[%]: Percentage value of the torque-
motor
[%] x 1.02
motor
®
MG80C502